Tightening apparatus for typewriter mountings



Sept. 22, 1953 J. H. PAGE TIGHTENING APPARATUS FOR TYPEWRITER MOUNTINGS Filed Aug. 29, 1951 2 Sheets-Sheet l fa/veeg@ Sept. 22, 1953 J, H, PAGE 2,653,067

TIGHTENING APPARATUS FOR TYPEWRITER MOUNTINGS Filed Aug. 29, 1951 2 Sheets-Sheet 2 Patented Sept. 22, 1953 TIGHTENING APPARATUS FOR TYPEWRITER MOUNTIN GS John H. Page, Muskegon, Mich., assigner to Shaw-Walker Company, Muskegon, Mich., a

corporation of Michigan Application August 29, 1951, Serial No. 244,226

(Cl. S12-Z8) Claims.Y

This invention relates to improvements in locking devices especially adapted for counterbalanced typewriter platforms of the kind wherein the platform with its typewriter can be removed from a retracted lowered position within a pedestal desk to an elevated writing position at the front of the desk.

More particularly, the invention relates. toy an improved locking device for holding the platform rigidly in writing position so as to eliminate objectionable instability often found in counterbalanced typewriter platforms of the kind above referred to.

A'common form of counterbalancing mechanism now in commercial use includes a pair of inwardly opening hooks carried at each. side of the typewriter platform, which hooks are moved into engagement with pins fixed on brackets o-n opposite sides of the pedestal compartment when the platform is in elevated writing position. Such devices usually have counterbalancing springs, and sometimes additional locking means, intended to hold the hooks seated against the pins to resist any movement or looseness of the platform while the typewriter is in use. In practice, however, such holding means are often insufficient for this purpose, or the parts become worn or get out of adjustment, so that the platform tends to wobble or vibrate when in its elevated writing position. y

The principal object of the present invention is to provide a simple and eflicient locking means, especially adapted for use in conjunction with or as an attachment to counterbalanced typewriter supports of the kind above referred to, wherein the operator may positively lock the retaining hooks against the retaining pins with a direct pull when the platform is in its extended elevated position.

Other objects and advantages of the invention will appear from time to time as the following description proceeds.

The invention may best be understood by reference to the accompanying drawings, in which:

Figure 1 is a plan view of the locking device as applied to a typewriter desk, with the top of the desk removed, and with parts thereof shown in section;

Figure 2 is a section taken on hne 2 2 of Figure 1;

Figure 5 is a fragmentary perspective view of iii) . 2 one of the supporting plates fixed on the inner sides of the desk.

Referring now to the embodiment of the invention illustrated in the drawings, my improved locking device is shown as applied to a commercial form of counterbalanced typewriter platform mechanism, in which a typewriter platform l!) is adapted to be swung from a retracted position within a compartment H of a pedestal desk, indicated generally at l2, into an elevated typewriting position, as shown in Figure 2.

The form of counterbalancing mechanism chosen herein to illustrate the use and operation of my locking device is substantially the same as disclosed in Patent No. 2,245,526, issued June 10, 1941, andv including a pair of metal brackets l5 which are connected to opposite sides of a transverse plate I6 at the rear end of the platform Ill. Said brackets are provided with upwardly extending arms Il having forwardly opened notches or hooks: i8 adapted to engage a pair of studs I9 on side plates 2l! which are fixed just within the front of the compartment II below the desk top 2|. Further details of construction of the counterbalancing mechanism need not be described in detail herein, as they form no part of the present invention and are fully described in the patent previously mentioned, excepting to point out that, when the platform I0 is'in its elevated position for normal operation of a4 typewriter thereon, as shown in Figure 1, the hoooks I8 are in engagement with the studs i9, and the associated linkage and counterbalancing springsI are intended to hold the hooks in engagement with said studs.

Certain modifications of counterbalancing mechanisms of the kind disclosed in the above pat-ent have also been used, including latching devices in the linkage system for holding the platform in its typewriting position, such as that disclosed in Patent Number 2,245,256, issued June 10, 1941, but such latching devices require that the outer end of the platform be raised by hand to release the latch. In any event, such latching devicesare disposed in the linkage system quite remote from the lsecuring hooks IB and their cooperating studs I9, so that there is no positive direct locking means to assure proper rigidity of the platform` in its typewriting position.

Referring now to the novel form of locking mechanism which constitutes the subject matter of the present invention, I provide an elongated base plate 25 which is seated on the transverse plate'l of platform I0, slightly below the level of the main upper supporting surface 26 of said platform. Said base plate is attached to the transverse plate It by a plurality of bolts 21, 21 extending through longitudinally elongated slots 28, 28 in the base plate so as to permit sliding adjustment of the base plate longitudinally of the platform I-l. The base plate 25 has upwardly extending flanges 29, 29 along opposite sides thereof which form guide members for a somewhat shorter sliding plate 3,0. is of generally inverted U-shape in cross section, with a top wall 3l, side walls 32 slid'abl'y engaging the outer faces of the base plate flanges 29, and with outwardly extending flanges 33, 33 at the lower ends of the side walls 32.

A locking lever 35 has its inner end pivoted at 35 to the extreme inner end of the base plate 25. Said lever has an upwardly offset main portion 3l extending forwardly and horizontally in spaced relation above the upper surface of the sliding plate 3?, with its free forward end extending beyond the front face of the compartment when the platform is in its elevated position, as shown in Figure l`. In the form shown herein, the forward end of the lever 35 has a control knob 35 disposed above the typewriter supporting surface 25 of the `platform lll.

A cam supporting plate, indicated generally at 39, is suitably xed' as by welding to the under face of the operating lever 35. This cam supporting plate has a channel member 4i) secured as by welding to its under face. Said channel member has a pair of opposed downwardly extending flanges 4l, di which form a horizontally disposed cam-like groove for receiving a guidev roller 4.5 rotatably mounted' on a stud 44 xed to the top wall 3l of the sliding plate 3i). The. channel member 45 has a portion 55 disposed generally tangentially to the pivotal axis of the operating lever 35. Said channel member is then continued with an outer portion 45 disposed at a forward oblique angle to the channel portion and at an angle of substantially less than 9() degrees to the longitudinal axis of the handle 35, as shown in Figure l.

A pair of locking bars 5i?, 50 are pivotally connected at their inner ends to the laterally extending danges 33, 33 of the sliding plate 30. The outer ends of these locking bars pass through arched brackets 5l, 5l which as shown herein are mounted on inturned flanges I5a, 15a of the bracket I5, l5 at the opposite side edges of the platform. lIhe locking bars 50, 55 have their rear edges formed with outwardly tapered cam surfaces 52, 52 at the outer ends thereof. The arched brackets 5I are of suiicient width to permit limited rockingv movement of the outer ends of the lockingu bars therein as said bars are moved from their forward unlocked position shown in dotted lines in Figure l, to their rearward fully locked position shown in full lines in the same figure. During the rocking movement and while in locked position, the locking bars fulcrum against the rear faces of the brackets 5I.

The extreme outer ends of the locking bars 50, 50 are adapted to project into locking engagement with suitable abutments carried on the side plates 25, 2G which carry the studs I9, I9 and are fixed within the front of the compartment l I, as previously described. In the form shown The latter plate Y herein, the locking abutments consist of elongated 4 the latter studs will be forced within the hooks I8, and rmly retained therein, when the locking bars 50 are moved to their fully extended locking position as shown in full lines in Figure l. The use and operation of the device may now be described as follows:

The locking device is intended for actuation after the platform l0 has been swung into its elevated typewrting position as shown in Fgure 2, with the hooks I8 in supporting engagement' with: the studs I9.

Figure 1Y shows in dotted lines the outer ends of the locking bars 5D, 5! in their fully retracted unlocked position, and in full lines their extended f locked position, respectively. The operating lever extends beyond the front face of the compartmenti'n position to be actuated by the user. The ehannelllz carried on the under face of the operating lever 35 has a portion lili disposed at an oblique angle to the lever 35 so that, when the lever is swung, in one direction, the guide roller 43 on the sliding plate Sli has a cam-like movement along the channel 52, causing the sliding plate to move inwardly and project the outer ends of the locking bars 591, 5i? throughl the brackets 5i into locking engagement Within the elongated slots 55, 55 in the side plates 2S), 20. When the lever is moved in the opposite direction, the movement of the locking bars 55, 5l] is reversed. The cam surfaces 52, 52 along the rear edges of the locking bars have both slidable and rocking movement while fulcrumed against the rear faces of the arched brackets 5l, 5I fixed on the platform, when the inner ends of the locking bars are moved laterally toward their locking position.

It will be observed that, due to the simultaneous rocking and endwise sliding movement of the outer ends of the locking bars while fulcruined within the brackets 5l' during the locking movement, the outer ends of said' locking bars are first moved rearwardly as they enter the slots 55, 55'Y and are then swung forwardly into engagement with the front endsl of said slots so as to take up any slack or looseness which might be present between the open hooks i3 and their cooperating studs E9, and hold them firmly in engagement with each other.

The inner, generally tangential portion of the guide channel i2 is arranged to permit slight arcuate movement of the rocking lever after it has reached its fully locked position, and yet retaining the parts in said locked position until positively released by reverse movement of the locking lever.

The proper final position of the outer ends of the locking arms can be adjusted by loosening the bolts 2l, 2l which secure the base plate 25 to the transverse plates l5 of platform IG and then tightening the bolts in the proper readjusted position wherein the pins IQ will be seated firmly Within the hooks I8 when the rocking lever 35 is swung to its fully locked position.

Although I have shown and describ-ed a certain embodiment of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of H the invention as defined in the appended claims.

I claim:

l.. In a locking device for a supporting platform movable endwise into extended position relative to a fixed base and including a plurality of inwardly facing open hooks at opposite sides of said platform engageable with studs xed on the base, the combination of a guide support slidably mounted centrally of the platform at its inner end, a pair of locking arms pivotally connected to opposite sides of said guide support, guide means for the outer ends of said locking arms fixed at opposite sides of said platform permitting simultaneous sliding lateral extension and rocking movement of said arms with the latter fulcrumed within said guide means, the outer ends of said locking arms being adapted for engagement with abutments on the fixed base when said locking arms are moved to extended position, a control lever pivotally mounted adjacent the inner end of said platform and having a free end extending into position for manual operation beyond said base when said platform is in extended position with respect to said base, said control lever having a cam member thereon, and a guide member carried on said guide support in engagement with said cam member to move the outer ends of said locking arms into locking engagement with said abutment means in a direction opposed to that in which said hooks are moved into engagement with said studs.

2. A locking device in accordance with claim 1, wherein the edges of said locking arms at their outer ends have tapered cam surfaces opposite the edges which have locking engagement with the abutments on the xed base to afford rocking and sliding engagement of said cam surfaces relative to the guide means on opposite sides of the platform, and cause the abutment engaging edges of said arms to be swung forwardly toward the abutments progressively with the lateral ex tension of said arms.

3. In a locking device in accordance with claim v1, wherein the cam member on the control lever consists of a guide channel having an end portion disposed generally tangential to the pivot of said lever, to permit limited movement of said lever in its fully locked position, While retaining the parts in locked position.

4. In a locking device in accordance with claim 1, wherein the slidable guide support is movably mounted on an elongated plate which is mounted for longitudinal adjustment on the platform, said control lever being pivotally mounted on said elongated plate so that the locking tension of the locking arms is controlled relative to their abutments when in fully locked position.

5. The structure of claim 1, wherein said control lever is adapted to be manually operated from the upper surface of the movable platform and adjacent, but spaced from, the fixed base.

JOI-IN H. PAGE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 197,695 Varney Nov. 27, 1877 382,101 McKnight May 1, 1888 612,987 Cary Oct. 25, 1898 1,015,961 Kelly Jan. 30, 1912 1,491,781 Axen Apr. 29, 1924 2,215,978 Schad Sept. 24, 1940 2,245,526 Fox June 10, 1941 2,271,241 Reitzel Jan. 27, 1942 FOREIGN PATENTS Number lCountry Date 178,143 Switzerland Nov. 16, 1935 

